Presently, research regarding the application of thermoelectric effect is in a whole new stage. In last few years, the thermoelectric technology has been focused on the development of high-performance thermoelectric materials. Thus, related measurement techniques of the time have been focused on the measurement of thermoelectric properties of thermoelectric materials. In recent years, thermoelectric research has changed from material-oriented to module-oriented. Namely, the development focus has been moved onto the overall performance of assembled thermoelectric modules.
A thermoelectric module is composed of a plurality of thermoelectric pillar P/N pairs, a plurality of metal electrode traces, a plurality of solder layers, and two ceramic substrates. The overall thermoelectric property after foregoing components are assembled is different from that of the original thermoelectric pillars. For example, an atom diffusion problem arises between the thermoelectric pillars and the solder layers and accordingly the thermoelectric performance of the thermoelectric pillars inside the thermoelectric module is reduced. Regarding thermal conduction between the cold side and the hot side of a thermoelectric module, unknown but obvious interface thermal resistances exist between the thermoelectric pillars and the solder layers, between the solder layers and the electrode traces, and between the electrode traces and the substrates. Thus, in an application, the actual temperature difference of the thermoelectric pillars is smaller than that applied to both sides of the thermoelectric module. As a result, the actual performance of the thermoelectric module is different from what is expected, and this difference cannot be accurately estimated.